1. Field of the Invention
The present disclosure relates to a cavitation device for forming a cavity on the surface of an underwater moving body for very high speed, and an underwater moving body having the same.
2. Background of the Invention
Examples of an underwater moving body include a cylindrical moving body which moves underwater, such as a torpedo and a self-propelled decoy. Such underwater moving body has large friction resistance due to friction by water viscosity. Since the friction resistance occupies most of the entire resistance of the underwater moving body, research to reduce the friction resistance is actively ongoing.
Such research is performed in an active manner, e.g., by a turbulence control method using micro bubbles or polymer ejection or an electromagnetic force, and in a passive manner using rivelets, nano protrusions, and paint coating. As a new approach to significantly reduce friction resistance generated underwater due to contact with water, being developed is a cavity generator for enabling an underwater moving body to move at a high speed by contacting the underwater moving body with vapor, rather than water, by forming a cavity on a partial or entire region of the surface of the underwater moving body.
However, cavitation devices which have been developed so far have the following problems.
Firstly, the conventional cavitation device causes a great change of lift and drag due to a great cavity size and shape change.
Furthermore, sever problems are occurred to the underwater moving body due to tail-slapping and slamming, the slamming occurring when the cavity implodes (collapses) due to disturbances.